Disclosed herein is a color LED driver, which is capable of being implemented by a compact structure without a feedback structure and accompanying a small size and low cost, by directly connecting a negative temperature coefficient (NTC) thermistor to a driving current path of a color LED applied to an LCD backlight to compensate a characteristic variation of the LED due to a variation in a temperature. The color LED driver includes a driving constant voltage source 100 which supplies a predetermined driving constant voltage VD; a driving circuit 200 which converts the driving constant voltage VD of the driving constant voltage source 100 into a plurality of driving currents, for driving color LEDs, the plurality of driving currents including red LED driving current Ird, green LED driving current Igd and blue LED driving current Ibd; a temperature compensation unit 300 which compensates variations in the red LED driving current Ird and the green LED driving current Igd due to a variation in a temperature, among the plurality of driving currents from the driving circuit 200; and an LED unit 400 including a plurality of color LEDs which are turned on by the driving currents from the temperature compensation circuit 300 and the driving current from the driving circuit 200.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A color LED driver, comprising: a driving constant voltage source for supplying a predetermined driving constant voltage; a driving circuit for converting the driving constant voltage of the driving constant voltage source into a plurality of driving currents, for driving color LEDs, the plurality of driving currents including red LED driving current, green LED driving current and blue LED driving current; a temperature compensation unit for compensating variations in the red LED driving current and the green LED driving current due to a variation in a temperature, among the plurality of driving currents from the driving circuit; and an LED unit including a plurality of color LEDs which are turned on by the driving currents from the temperature compensation circuit and the driving current from the driving circuit, wherein the temperature compensation unit comprises: a first temperature compensation circuit including a first NTC thermistor for compensating the red LED driving current according to the variation in the temperature and a first linear compensation resistor which is connected to the first NTC thermistor in parallel, for compensating linearity of the red LED driving current; and a second temperature compensation circuit including a second NTC thermistor for compensating the green LED driving current according to the variation in the temperature and a second linear compensation resistor which is connected to the second NTC thermistor in parallel, for compensating linearity of the green LED driving current.
2. The color LED driver according to claim 1 , wherein the first NTC thermistor has temperature sensitivity higher than that of the second NTC thermistor.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 24, 2007
January 18, 2011
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